Cod sursa(job #3209777)
Utilizator | Andrei Pirjol andreipirjol5 | Data | 3 martie 2024 15:17:12 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.59 kb |
#include <fstream>
#include <vector>
using namespace std;
ifstream fin ("ciur.in");
ofstream fout ("ciur.out");
const int NMAX = 2 * (1e6);
vector <bool> ciur;
void Ciur(int n)
{
ciur[1] = 1;
for(int i = 2; i * i <= n; i++)
if(ciur[i] == 0)
for(int j = 2 * i; j <= n; j += i)
ciur[j] = 1;
}
int main()
{
int n;
fin >> n;
ciur.resize(n + 5);
Ciur(n);
int cnt = 0;
for(int i = 1; i <= n; i++)
if(ciur[i] == 0)
cnt++;
fout << cnt;
fin.close();
fout.close();
return 0;
}